Display screen or portion thereof with transitional graphical user interface



1. Display screen or portion thereof with transitional graphical user interface

1.1 : Front

1.2 : Front

1.3 : Front

1.4 : Front

The ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described; The outer perimeter shown in broken line in the drawings illustrates a display screen or portion thereof and forms no part of the claimed design; The remaining broken lines in the drawings illustrate portions of the graphical user interface that form no part of the claimed design; FIG. 1 is the image in a sequence for a display screen or portion thereof with transitional graphical user interface showing our new design; FIG. 2 is the second image thereof; FIG. 3 is the third image thereof; and, FIG. 4 is the fourth image thereof; The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1-4 ; The process or period in which one image transitions to another image forms no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described. 